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amanda1
Rank 2
May 29, 2023
Solved

Flow Temperature settings of my Mitsubishi Ecodan heat pump set correctly?

  • May 29, 2023
  • 37 replies
  • 12840 views

Can anyone tell me what these particular settings mean please see photo 1 of FTC6 controller (I am still on the ASHP learning curve) - I am trying to grapple with whether the Flow Temperature settings are too high/too low/just right. At the moment the outside temperature during the day has been about 18 degrees, at night we have been having near freezing temperatures. See photo 2 from Melcloud. My system is set to run 24/7 which I believe is the most economical way - low and slow. I have been having the room control set to 17 in the day and I have put it up to 18 in the evening during my off peak hours. if I move it up or down it’s only by half a degree.  My problem is that I previously had old storage heaters and this thing is using a fraction of the electricity that they were using, so all the angst about 2.5kwh usage on this forum seems irrelevant to my situation. With my storage heaters I was using 40kwh a day on May 1st, if which 7kwh was all the other stuff including oven. The Ecodan was fitted on 2nd, and now my usage (total) is currently between 8 and 10kwh a day. Happy days! But I am trying to find out as much as I can about the way the current settings are working, preparatory to the Winter when we frequently have as many as 20 days a month with below zero temperatures.  Snow lying many times between November and April. The Melcloud app is quite un-user friendly. I will go into the settings myself before winter to adjust if need be. I have already changed the legionella settings following Heat Geek video, once every 15 days to 60 degrees time 1 hour during off peak, holding for 5 minutes; that should save some money. What I want to do before winter is set up the weather compensation mode. At the moment though I am wondering what the Flow temperature settings on the right of the control panel mean. And if the flow temperature is low enough, too high, or too low - see photo three where something exciting seemed to be happening at around 2.30pm even though I didn’t change anything….!Presumably the water heating up as it had dropped below 40.

(as per advice on heat geek site for hotter weather).

 

    Best answer by M.isterW

    The first thing to tell you is how the melcloud app works. It doesn't change the settings on the FTC. It overrides them with messages from a cloud server. So my recommendation is to make changes on the FTC and only use melcloud for monitoring.

     

    Are you using weather compensation mode or auto adapt, with a Mitsubishi internal temp sensor?

    Are your rooms getting to the correct temperature and staying there?

    37 replies

    Show previous replies
    Jeffus
    Rank 20
    Jeffus
    Rank 20
    January 29, 2024

    Ah! Thats why flow temp shot up to 48…. Nothing to do with comp curve settings… interesting. 🤨 so thats really confused me as to how other ppl have told me to set the curve but use aa mode so flow temp is low.. one guy said set room temp to 28.. they must have individual room stats or something?! Thank you for taking time to reply, much appreciated 

    It will adjust the flow down on AA so see what happens over time, it won't stay at 48, it just doesn't use those tweaks to the curve that you have set in the weather compensation.

    You could contact the manufacturer to be absolutely sure. That is always a good idea

      juliamc
      Rank 20
      juliamc
      Rank 20
      January 29, 2024

      You’re so right, although it seems counterintuitive that keeping a hp running all the time is cheaper than having it on a schedule. Maybe it could be compared to only switching on the fridge for a few hours a day but still constantly opening the door. 
      There should be an idiots guide to using a heat pump handed out with each installation. I think I might write one !!

      Ah yes, I see what you mean re the pallets. My outdoor unit is installed in a fairly enclosed yard so I’m trying to improve the airflow around it.

      There is one, ‘Bodge Busters’!

      I haven’t looked at Bodge Busters but I do know the authors’ website which has lots of useful information and knowledgeable people on its forum. A heat pump owner shouldn’t have to wade through a whole book though, BB would have to cover many types of installations and manufacturers, I assume it does.
      Owners just need clear instructions for their own system. Installers are supposed to provide handover documents with that kind of info in, my installers didn’t. There’s a multitude of new hp owner’s floundering in the dark not knowing what they’re doing.

      P
      Newcomer
      Pluto
      Newcomer
      March 16, 2026

      Hi, 

      New to the forum. I have an Ecodan for the last 3 years without much problem. Heats 2 zones and DHW. A few weeks ago I had a low flow error that i got a technician to fix, He cleaned the pipes out and it’s back to good flow, but since then i have noticed that when the water is heating, the heat pump comes on for about 15-20 mins, then it switches to immersion for 15-20 minutes and back and forth until the water is back to 50 Degrees. See graph below. I’m wondering is there a setting in the FTC5 that he might have switched while troubleshooting and forgot to reset. 

      Thanks in advance for any help/thoughts

       

      BPLightlog
      Super User
      BPLightlogSuper User
      Super User
      March 16, 2026

      Hi ​@Pluto , if you’ve checked the set point and reheat settings, it might be something that’s moved on the hot water cylinder sensor which falsely indicates that it’s up to temp.

      Do you know your flow rate? Just wondering if the rate might be near minimum still.

      Bring me Sunshine ~ E&E {Solar PV, Battery Storage, Hybrid EV, ASHP and Home Assistant automation}
      P
      Newcomer
      Pluto
      Newcomer
      March 16, 2026

      Set point is 51, temp drop 10 Degrees and i just checked flowrate as the water was heating - it was 13L

        BPLightlog
        Super User
        BPLightlogSuper User
        Super User
        March 16, 2026

        13l/min should be good enough.

        What about the cylinder sensor? If it got moved slightly, it might give false ‘target achieved’ readings as the DHW is heating - at that point the system would switch back to alternative heating before the false ‘target achieved’ lowers before getting to real target. That would create the on/off effect.

        Another alternative might be if the 3 way diverter valve is not switching cleanly

        Bring me Sunshine ~ E&E {Solar PV, Battery Storage, Hybrid EV, ASHP and Home Assistant automation}
          Abby_OVO
          Community Manager
          Abby_OVO
          Community Manager
          March 17, 2026

          Hey ​@Pluto 

           

          I’m glad to see BPLightlog has already stopped by with some helpful advice.

           

          I hope it’s been useful so far and helps get you to the route of the cause and how to stop it if you’re not wanting it to come on like that every time. 

           

          Do let us know how you get on or what more you find.

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